Bridges are common and have different designs. One type of bridge is known as the short span bridge which has a relatively short span of, for instance, 80 feet. There are basically two styles of composite short span bridges predominately in use. Both types use supporting longitudinal wideflange beams or girders as the main support of the bridge decks.
The first type uses wood such as plywood sheets or metal forms or both kinds of forms between the girders to provide the forms as support for the steps of installing reinforcing steel and pouring concrete to construct the bridge deck (hereinafter referred to as “Type 1” construction). Typically, four longitudinal steel girders span two steel piers that are made of steel girders. A concrete deck is poured in place on top of the four steel girders. The concrete deck is secured to the steel girders generally by shear studs welded in the vertical position to the top flange of the steel girders and imbedded in the steel reinforced concrete deck. The structural steel in the Type 1 bridge can be erected quickly once the concrete footings/piers are poured and ready for erection of the steel. Such a construction, however, requires a great deal of labor to form the roadway or deck out of plywood and to install the reinforcing steel before pouring and finishing the concrete to create the deck. After the concrete is poured, bridge barrier rails must be formed, reinforcing steel installed, and concrete poured and finished. All the wood forms and the supporting falsework have then to be removed after the concrete is cured to reach its required strength, which may take as long as 30 days.
In the other type, the longitudinal steel girders are covered with corrugated steel bridge flooring, which is used as a form generally welded on top of and across the girders. Asphalt aggregate or concrete is then poured over the bridge flooring which remains in place as part of the bridge (hereinafter referred to as “Type 2” construction).